py26-matplotlib +qt4 runtime error

[mf2k (Frank Schima)]

I see the following error when i try to use the qt4agg backend in py26-matplotlib.

  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/backends/backend_qt4agg.py", line 130, in draw
    FigureCanvasAgg.draw(self)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/backends/backend_agg.py", line 314, in draw
    self.figure.draw(self.renderer)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/artist.py", line 46, in draw_wrapper
    draw(artist, renderer, *kl)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/figure.py", line 773, in draw
    for a in self.axes: a.draw(renderer)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/artist.py", line 46, in draw_wrapper
    draw(artist, renderer, *kl)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/axes.py", line 1735, in draw
    a.draw(renderer)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/artist.py", line 46, in draw_wrapper
    draw(artist, renderer, *kl)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/axis.py", line 742, in draw
    tick.draw(renderer)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/artist.py", line 46, in draw_wrapper
    draw(artist, renderer, *kl)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/axis.py", line 196, in draw
    self.label1.draw(renderer)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/text.py", line 515, in draw
    bbox, info = self._get_layout(renderer)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/text.py", line 272, in _get_layout
    'lp', self._fontproperties, ismath=False)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/backends/backend_agg.py", line 158, in get_text_width_height_descent
    font = self._get_agg_font(prop)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/backends/backend_agg.py", line 195, in _get_agg_font
    fname = findfont(prop)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/font_manager.py", line 1304, in findfont
    _rebuild()
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/font_manager.py", line 1288, in _rebuild
    fontManager = FontManager()
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/font_manager.py", line 980, in __init__
    self.ttffiles = findSystemFonts(paths) + findSystemFonts()
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/font_manager.py", line 337, in findSystemFonts
    for f in get_fontconfig_fonts(fontext):
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/font_manager.py", line 299, in get_fontconfig_fonts
    output = pipe.communicate()[0]
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/subprocess.py", line 686, in communicate
    self.wait()
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/subprocess.py", line 1157, in wait
    pid, sts = os.waitpid(self.pid, 0)
OSError: [Errno 4] Interrupted system call

$ port installed py26-matplotlib 
The following ports are currently installed:
  py26-matplotlib @0.99.1.1_1+cairo+ghostscript+gtk2+latex+qt4+tkinter (active)

Any ideas?